## Facts

- The City of Thornton planned the “Northern Project,” a large municipal water-supply project intended to secure long-term water for a growing population.
- Thornton acquired irrigation water rights by purchasing more than 100 farms served by the Water Supply and Storage Company on the Cache la Poudre River and sought to change those rights to municipal use.
- Thornton also sought adjudication of new conditional water rights and exchanges connected to the project.
- The applications raised disputes about historic return flows, proposed treatment of imported (transmountain) water, and asserted needs for replacement water to protect certain wells.
- The Water Division 1 water court consolidated multiple cases and entered a comprehensive decree approving the changes and conditional rights, subject to extensive operational and protective conditions, including volumetric limits, water-quality constraints, limits on transmountain-water reuse, replacement-water requirements for certain nontributary wells, and a requirement that Thornton pay the division engineer’s administration costs.
- Thornton appealed several conditions; numerous objectors cross-appealed challenging approval of the rights and the adequacy and legality of various conditions.

## Issues

1. Whether the water court could impose volumetric limits and operational “reality checks,” including a total annual yield cap, as conditions on changed and conditional rights.
2. Whether Thornton, as an importer/owner of transmountain (foreign) water, could be denied the right to reuse and successively use that water.
3. Whether the decree could require Thornton to provide replacement water to protect nontributary wells not shown to have a legally protected entitlement.
4. Whether the water court could condition the decree on Thornton paying the division engineer’s costs to administer the decree.
5. Whether the decree otherwise properly approved Thornton’s conditional rights and changes of use and applied antispeculation and injury-prevention standards.

## Decision

- The Colorado Supreme Court affirmed in part, reversed in part, and remanded.
- The Court affirmed approval of Thornton’s changes of use and new conditional rights, and upheld most decree terms designed to prevent material injury and protect water quality.
- The Court upheld use of volumetric limits and “reality checks” as permissible injury-prevention tools, but required modification of a total yield limitation that lacked adequate evidentiary support.
- The Court reversed the decree’s restriction on Thornton’s right to reuse transmountain water.
- The Court reversed the requirement that Thornton provide replacement water to nontributary wells lacking a legally protected claim requiring such replacement.
- The Court reversed the requirement that Thornton pay the division engineer’s administrative costs, holding the condition exceeded judicial authority absent statutory authorization.
- The case was remanded to revise the decree consistent with these holdings.

## Legal Principles

- Water courts may approve changes of water rights and conditional rights while imposing terms and conditions reasonably supported by the record to prevent material injury to vested rights and to address operational and water-quality concerns.
- Volumetric limits and operational “reality checks” are permissible conditions when tied to demonstrated need and available supply; conditions must be supported by evidence and may not be arbitrary.
- Imported (transmountain/foreign) water generally carries a right in the importer to reuse and successively use the water; denial of reuse cannot rest on an “original intent to reuse” requirement inconsistent with the foreign-water doctrine.
- A change decree may not be used to require replacement water to protect nontributary wells absent a legal basis establishing a cognizable injury or entitlement requiring protection.
- Courts cannot impose cost-shifting for state administrative functions as a condition of a water decree without statutory authority.

## Conclusion

The court largely sustained a comprehensive decree for a major municipal water project and confirmed broad authority to impose evidence-based protective conditions, but it also clarified that imported-water reuse rights may not be curtailed on an intent-to-reuse theory and that courts may not impose unauthorized replacement-water duties for nontributary wells or require applicants to pay state administration costs absent legislative authorization.


City of Thornton v. Bijou Irrigation Co., 926 P.2d 1 (Colo. 1996)